An army of hundreds of millions of ants: The dunes of Mauguio-Carnon, a town on the outskirts of Montpellier in France, have become the latest battleground for these tiny invaders. The ant colonies have also spread their conquest to Lyon, Bordeaux, Corsica, Strasbourg, and even other European countries like the Netherlands, Italy, and Switzerland.
Luc Gomel, an ant specialist from Paul Valéry University, revealed the staggering scale of the infestation. “It is estimated that this nest spans approximately 800 meters and houses at least a few hundred million ants,” he shared with France 3, a local news outlet.
“Ordinary ant populations usually number in the hundreds or tens of thousands. Here, we are dealing with unprecedented numbers. These ants form an overwhelming mass, overpowering and displacing other ant species they come across. Their presence can have detrimental effects on other insects they prey upon for sustenance. Furthermore, this domino effect may extend to certain plant species.”
The invasive species responsible for this ecological disruption is Tapinoma magnum. Native to the Mediterranean basin and North Africa, these small, black ants, measuring less than 0.1 inches, have rapidly multiplied and established dominance, outcompeting and decimating local ant populations. Additionally, they emit an unpleasant odor reminiscent of rancid butter.
Jean-Yves Bichaton, in charge of the PACA-Corsica region at the French Observatory of Biodiversity (OFB), shed light on the recent identification of Tapinoma magnum. “It was only distinguished as a separate species in 2017,” he revealed to DayFREuro. “Previously, it was mistaken for three other ants: Tapinoma nigerrimum, Tapinoma darioi, and Tapinoma ibericum.”
While the exact means of their introduction to France remain uncertain, humans likely played a role in the Mediterranean crossing, according to Bichaton.
The voracious appetite of Tapinoma magnum presents a profound challenge as they consume various plant species, including fruit trees, while eliminating other vital species that maintain ecological balance, such as spiders.
“A Tapinoma magnum colony can house several hundred, or even several thousand, queens since its establishment,” Bichaton explained.
Ironically, attempts to eradicate these invasive ants often exacerbate the problem. Cyril Berquier, an entomologist at the Corsican Environment Office, warned against counterproductive measures. “Many people unintentionally worsen the situation,” he cautioned during an interview with France 3 in 2020. “They use products that not only eliminate the local ant species that were still present but also inadvertently promote the proliferation of Tapinoma magnum. They may kill a few of these ants, but the subsequent year, the population doubles according to their own observations.”
This unintended consequence arises from the fact that Tapinoma magnum thrives in “degraded” environments with reduced biodiversity—a condition inadvertently created by the use of insecticides.
Berquier advised a more targeted approach when dealing with a significant Tapinoma magnum infestation. “If the problem is severe, it may be necessary to adopt localized treatment, identifying the specific anthills—often found at the edges of concrete—and only treating those areas without harming other ant species,” he suggested. “Consistently mowing your lawn short diminishes ant diversity and promotes Tapinoma magnum growth. It inadvertently fosters aridity, which further sustains their development.”
To combat this formidable foe, understanding the enemy—Tapinoma magnum—and preserving biodiversity among allies remains vital.
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